Fungus threat to frogs widespread in Western Ghats

Deadly pathogen is highly diverse

July 07, 2018 08:36 pm | Updated 08:36 pm IST

Amboli toad tested positive for the chytrid fungus.

Amboli toad tested positive for the chytrid fungus.

The discovery of the dreaded chytrid fungus, which is notorious for causing frog declines and extinctions worldwide, in frogs in the Western Ghats got Indian scientists worried seven years ago. Now, a team has detected the pathogen in all major biodiversity hotspots in India.

A study published this week in the journal Scientific Reports reveals that the chytrid fungal pathogen Batrachochytrium dendrobatidis (Bd, which causes the infectious and fatal skin disease chytridiomycosis) is present in frogs across the Western Ghats, Eastern Ghats, Himalaya, northeastern hill ranges, and the Andaman and Nicobar Islands.

Scientists from multiple institutes including the Laboratory for the Conservation of Endangered Species at Hyderabad’s Centre for Cellular and Molecular Biology, obtained the results from 1,870 skin swab samples of 111 species of frogs across 147 locations in India. They handled the frogs carefully with fresh gloves, and swabbed each animal 70 times to capture traces of the pathogen. Of these, 158 samples tested positive for Bd.

Low incidence

Genetic analyses of the pathogens showed that they are extremely diverse in India. Of the 57 related types of Bd found, 46 were unique to India alone, while others matched those reported from countries such as the U.S. and Japan. The pathogen is most prevalent in a family of dancing frogs (Micrixalidae) which is endemic to India, and increased with the onset of the monsoon. However, Bd is prevalent only at a “low level” in all the country’s hotspots, the scientists say.

“While there might not be a need for immediate panic because we are yet to see mass die-offs, it is important to stay vigilant and map the various strains of Bd,” wrote co-author Dr. Lilly M. Eluvathingal, Assistant Professor, Occidental College, California, in an email.

Sustained study

It would also be important to keep studying newly-described amphibians, observe their natural history, estimate populations, and gauge their interactions with other species and the habitats in which they reside, she added.

This is the second study published over the last month on chytrid in India. A study published on June 13 in the international journal Royal Society Open Science also said that the fungus is “widespread but [of] low intensity” in the northern Western Ghats.

Fourteen of the 21 species that scientists studied in Maharashtra tested positive for the pathogen; these included the critically endangered endemic Amboli toad and four species of caecilians (limbless, snake-like amphibians).

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